Presque Isle State Park, all 3,200 acres of it, is expected to reopen at 7 p.m. today after being closed for much of the day.

Park officials said a helicopter operator spent several hours spraying herbicide on invasive plants in the park, specifically narrow-leaf cattail and phragmite plants.

Assistant Park Manager Holly Best, who was present when the helicopter lifted off at about 12:30 p.m. from Beach 11, said the chemicals being applied with the helicopter inhibit the growth of plant cells.